U.S. adults with a diet high in trans fatty acids are more than twice as likely to develop type 2 diabetes than adults with a diet low in trans fatty acids, according to findings published in the Journal of Diabetes.

“Higher plasma concentrations of trans fatty acids, an objective marker of trans fatty acid intake, are associated with insulin resistance and diabetes in U.S. adults,” Wei Bao, MD, PhD, assistant professor at the University of Iowa College of Public Health, told Endocrine Today. “Reducing trans fatty acids intake may improve glucose metabolism and lower the risk of diabetes.”

Bao and colleagues analyzed data from 3,801 adults participating in the 1999-2000 and 2009-2010 cycles of the National Health and Nutrition Examination Survey (mean age, 50 years; 48% men). Researchers assessed available data on total and individual trans fatty acid concentrations, including palmitelaidic acid, elaidic acid, vaccenic acid and linoelaidic acid, as well as information on self-reported diabetes status, fasting plasma glucose and HbA1c. Researchers used logistic regression analysis to estimate ORs for diabetes according to quintiles of plasma trans fatty acid concentrations, as well as linear regression analysis to estimate the association between trans fatty acids and glucose metabolism biomarkers in adults without diabetes.

In comparing the highest quintile of total trans fatty acid concentration with the lowest quintile, researchers observed that adults in the highest quintile were more than twice as likely to develop diabetes (OR = 2.19; 95% CI, 1.27-3.79), with risk persisting after adjustment for demographics, socioeconomic status, lifestyle and dietary factors, and family history of diabetes. Additional adjustment for BMI moderately attenuated the risk, with an OR of 1.83 for adults in the highest quintile vs. the lowest quintile (95% CI, 1.04-3.21).

In comparing individual trans fatty acids, researchers found that adults in the highest quintile of elaidic acid were more likely to develop diabetes vs. those in the lowest quintile (OR = 2.34; 95% CI, 1.48-3.72). In a multivariable model including the four trans fatty acid isomers, researchers observed associations between only elaidic acid and diabetes (OR = 3.27; 95% CI, 1.64-6.51), with no differences when adjusting for age, sex or race.

The researchers also conducted analyses to examine whether the FDA final rule requiring nutrition labels to list all trans fatty acids, published in January 2006, had an effect on trans fatty acid consumption and diabetes risk. In the 1999-2000 NHANES, the adjusted OR for the diabetes for the highest quintile of trans fatty acid concentration was 2.54 (95% CI, 1.07-6.03) compared with the lowest quintile. For the 2009-2010 NHANES, the adjusted OR for the diabetes for the highest quintile of trans fatty acid concentration was 1.59 (95% CI, 0.94-2.68) compared with the lowest quintile. Additionally, researchers observed associations between total plasma trans fatty acids and fasting glucose, fasting insulin, HbA1c and homeostatic model assessment of insulin resistance in adults without diabetes.

“Continued biomonitoring of trans fatty acids in humans is needed,” Bao said. “Plasma concentrations of trans fatty acids reduced substantially between 1999-2010 and 2009-2010. It is imperative to understand how the changes in trans fatty acid concentrations are related to cardiometabolic health in U.S. adults. Second, trans fatty acids have many isomers, and they come from different sources (eg, ruminant or industrial trans fatty acids). Health effects of specific trans fatty acid isomers remain to be determined, which will be important for guiding food choices.” – by Regina Schaffer

For more information:

Wei Bao, MD, PhD, can be reached at the University of Iowa College of Public Health, 145 N. Riverside Drive, Iowa City, IA 52246; email: wei-bao@uiowa.edu.